Secretion of AIMP1 N-terminal fragment from Wnt-activated HFSCs. (a) AIMP1 secretion by incubating HFSCs under different conditions. The proteins in the whole cell lysates (WCL) and supernatant (SUP) were subjected to WB analysis with the antibodies specific to the N-terminal (N-AIMP1) and C-terminal regions of AIMP1 (C-AIMP1). Wnt3a: 200 ng/ml, FGF7: 100 ng/ml, Noggin: 200 ng/ml, TGFβ2: 10 ng/ml, SHH: 200 ng/ml. (b) HFSCs were transfected with AIMP1 siRNA (10 pmol) and treated with Wnt3a (200 ng/ml). WB was performed with the N-AIMP1 antibody. (c) AIMP1(400 μg) was incubated with each of MMP1 (72.9 ng), MMP2 (100 ng), and MMP9 (106 ng) at 37 ℃ for 4 h and WB analysis with the N-AIMP1 antibody. (d) AIMP1 was incubated with recombinant MMP1 and different amounts of anti-MMP1 antibody. AIMP1 protein was detected by N-AIMP1 Antibody. (e) AIMP1 was incubated with MMP1 in the absence or presence of ARP100 (A, 1.5 μg, MMP1 and MMP2 inhibitor) and doxycycline hyclate (D, 1 μg, MMP1, MMP9 and MMP12 inhibitor). (f) Secretion of AIMP1 fragment was confirmed by WB in the absence or presence of ARP100.